Electrode rapping system



Jan. 11, 1955 F. w. SCHMITZ ELECTRODE RAPPING SYSTEM 2 Sheets-Sheet 1 Filed Dec. 20, 1951 INVENTOR Eea'eriok st/zmflfa ATTORNEYS Jan. 11, 1955 F. w. SCHMITZ 2,699,224

ELECTRODE RAPPING SYSTEM Filed D66. 20, 1951 2 Sheets-Sheet 2 f 10 ('onfraller INVENTOR Frederik 5071777172 ATTORNEYS United States Patent '0 ELECTRQDE RAPPING SYSTEM Frederick W. Schrnitz, Plainfield, N. J., assignor to Research Corporation, New York, N. Y., a corporation of New York Application Dec-anther 20, 1951, Serial No. 262,535

2 Claims. ((31. 183-7) This invention relates to electrode rapping systems and more particularly to a system for rapping the electrodes of an electrical precipitator employing a pneumatically powered rapper that strikes spaced, discrete blows of a piston against an anvil that is in impact transmitting relation to the electrode to be rapped.

An object of the invention is to provide an electrode rapping system that eifectively vibrates or raps either the collecting or the discharge electrodes of an electrical precipitator.

Another object is to provide an electrode rapping systemespecially adapted to be automatically controlled.

Yet another object is to provide an electrode rapping system employing a pneumatic impact rapping device having a reciprocating piston, which system may have a single source of compressed gas for moving the piston through both its impact stroke and its return stroke.

Another object is to provide a rapping system in which the rapping energy is readily varied.

Another object is to provide an electrode rapping systom that is simple and economical to fabricate, install and operate and that has a long service life with a minimum of maintenance requirements.

A typical rapping system in accordance with the invention includes a cylinder, a free piston in the cylinder, means supplying a substantially constant low fluid pressure to the cylinder at one end of the piston, and means supplying intermittently a substantially higher fluid pressure to the cylinder at the other end of the piston. The cylinder is vented at the end at which the intermittent higher pressure fluid is supplied.

in the drawings:

Fig. 1 is an axial sectional view of a rapping device that may be embodied in the system of the invention;

Fig. 2 is a View of an electrode rapping system in accordance with the invention;

Fig. 3 is a plan view of an electrical precipitator embodying an electrode rapping system in accordance with the invention, parts being broken away to show interior construction; and

Fig. 4 is an elevational view tator shown in Fig. 3.

Referring to the drawings, particularly to Fig. 1 thereof, the illustrated rapping device, designated by the general reference numeral 10, has a rapper bar 11 that may be Welded or otherwise suitably afiixed at the left-hand end to an object to be rapped (not shown). The object to be rapped may be a collecting electrode of an electrical precipitator, a discharge electrode of an electrical precipitator, or an electrode system including such electrodes.

The right-hand end 12 of the rapper bar is welded as at 13 to an anvil disc 14. A hollow cylinder 15 having 3 cylinder head 16 is fastened by bolts 17 to the anvil isc.

Within the cylinder is a free piston 13 having a central portion 19 of a diameter providing a close sliding lit with the interior walls of the cylinder and terminal portions 20 and 21 of somewhat smaller diameter.

A high pressure fluid inlet port 22 admits fluid from the pipe 23 to the chamber 24 provided in the cylinder at the right-hand end of the piston. The chamber 24 is vented to atmosphere through a vent port 25.

Low pressure fluid is admitted to the chamber 26 at the left-hand end of the piston through a port 27 communicating with a pipe 28 supplying low pressure fluid.

Referring to Fig. 2, pipe 29 is connected to a source (not shown) of high pressure fluid, preferably compressed of the electrical precipi- 2,699,224 Patented Jan. 11, 1955 air. Pipe 30 connects pipe 29 to one side of a pressure reducing or pressure controlling valve 311, the other or low pressure side of the valve being connected to pipe 25.

A pipe 32 connects the source of high pressure fluid to one side of a second pressure controlling valve 33. The reduced pressure side of valve 33 is connected by a pipe 34 through a solenoid valve 35 to the pipe 23.

The solenoid valve is of the on-oil type and is operated by a solenoid 36 energized through wires 3'7. This type valve is conventional and is on or open when the solenoid is energized and off or closed when the solenoid is deenergized. The solenoid is energized and deenergized by any suitable manual or automatic switch means (not shown).

In order to damp vibrations that tend to travel back through the fluid supply system from the rapper device 1% and also to insulate the rapper device electrically from the fluid supply system, rubber garden hose may be sub stituted for the pipes 23 and 28.

In operation, compressed air at p. s. i. gage is connected to the pipe 29. Valve 31 is adjusted to provide a pressure of about 5 p. s. i. gage in the pipe 28 and cylinder chamber 26. Valve 33 is adjusted. to provide a pressure of about 80 p. s. i. gage in the pipe 34. With the solenoid valve 35 closed, the low pressure air in cylinder chamber 26 holds the piston 18 at the right-hand end of the cylinder in the position shown in Fig. 1.

To produce a rapping impact of the piston 18 against the anvil plate 14, the solenoid 36 is energized to open the valve 35 and admit a slug of high pressure compressed air to the cylinder chamber 24. The high pressure air drives the piston to the left and forcibly against the anvil plate 14- to produce vibrations that are transmitted through the rapper bar 11 to the object to be rapped.

During movement of the piston to the left, air in the chamber 26 is displaced into the pipe 28 which has sufiicient volume between the port 27 and the valve 31 to accommodate the displaced air with only negligible increase in pressure.

The solenoid 36 is deenergized, valve 35 closes and the pressure in chamber 24 quickly falls to atmospheric pressure, the air in the chamber being bled to atmosphere through the vent port 25. Low pressure air in the chamber 26 returns the piston 18 to the right-hand end1 of the cylinder and the rapper is ready for another cyc e.

It will be understood that the cross-sectional area of vent port 25 is chosen small enough so that no great loss of pressure occurs in the chamber 24 during the power stroke of the piston but large enough to provide for reasonably rapid return of the piston to starting position when the high pressure air is cut ofi.

It will be seen that the present invention provides a rapping system in which the motion of the piston may be in a horizontal direction which, for many applications, is the most favorable direction of rapping. It is of course possible for the rapping device to be oriented vertically or at some acute angle to the horizontal, if desired.

The energy of impact of the piston may be changed by varying the pressures applied to the piston. The pressures given hereinbefore are merely exemplary for a rapper that is horizontally mounted. Increasing the pressure of the intermittent slugs of air cylinder raises the impact energy of the piston; conversely, decreasing the pressure lowers the energy. A constant low pressure of about 5 p. s. i. gage is approximately correct for a horizontally mounted rapper; for vertical mounting with a downward impact stroke of the piston, the piston return pressure should be about 5 p. s. i. gage plus the pressure required to hold the piston up against gravity.

Reterring particularly to Figs. 3 and 4, the electrical precipitator shown has a shell or housing 38 enclosing conventional plate electrodes 39 and complementary dis charge electrodes 40. As is well known in the art, gas bearing suspended material is passed between the complementary electrodes and the suspended material is electrically precipated on the plate electrodes 39. These electrodes are rapped to keep them in a clean condition. For this purpose, the rapper bar 11 is welded to the edges of applied to the vented end of the i a plurality of aligned plate electrodes 39. The rapper bar extends outwardly through a hole 41 in the side of the precipitator shell 38 and terminates in the rapper device 10.

The precipitate! shown has six sections of two banks each of complementary electrodes. Since each bank of collecting electrodes requires one rapper device, twelve such rapper devices are provided as shown in Figs. 3 and 4.

The rapper devices 10 are supplied with operating gas froma compressed air supply 42. Air from the source 42 flows through a pipe 43 under control of manually operated valve 44 to a water separator 45 in which condensed water is removed from the air. The air then flows through a pressure regulating valve 33a in which the pressure is dropped slightly to a high pressure working value of 20 to 80 p. s. i. gage, for example. High pressure air of regulated pressure flows through the riser 46 to the branch horizontal high pressure main 47 from which it. is fed to the rapper cylinders 10a to 10 seen in Fig. 4.

Taking the rapper cylinders 10a and 10b for example, air flows through the pipe 48, manual valve 49, air filter 50, and oiler 51 to the T-junction 52 in which the flow of air is split and delivered to the solenoid valves 35a and 35b associated, respectively, with the rapper cylinders 10a and 10b. The rapper cylinders 100 to 10 are similarly supplied with high pressure air.

Riser 46 delivers into a branch horizontal low pressure main 53 through a hand valve 54, air filter 55, and pressure regulating valve 31a, the latter dropping the pressure in the low pressure main 53 to a working value of from 3 to 10 p. s. i. gage, for example. From the main 53, low pressure air is supplied to the rappers 10a to 101 through pipes 28a .to 28].

The solenoid valves 35, providing for admission of slugs of high pressure air to the rapper cylinders, are energized and controlled from a controller 56. Direct current for energizing the solenoids is supplied to the latter from the controller 56 through a wire 57 that is a common lead to the solenoids and separate wires 58a to 58 leading respectively to the several solenoid valves 35a to 35].

The construction and arrangement of rappers at the back of .the precipitator is substantially identical to that at the front. Operating air is supplied to the rappers at the back through a lateral pipe 59 that connects with the riser 46. The solenoid valves associated with the rappers at6 the back are energized and controlled by the controller Controller 56 is conventional and includes a timer that energizes and deenergizes the solenoids of valves 35 Valves 54 and 49 are opened and low pressure regulating valve 31a is set .to establish in main 53 the required low pressure for returning the rapper piston to starting position. The controller 56 is put in operation to actuate the rappers on a predetermined cycle of operation that is determined by routine observation to be suflicient to maintain the collecting electrodes 39 in a satisfactory state of cleanliness.

From the foregoing description, it will be seen that the objects of the invention, as stated or implied, are fully realized in the rapping systems disclosed herein by way of illustration. It will be understood that the principles of the invention may be applied in a variety of modificatioilslwithout departing from the spirit and scope thereof.

1. Means for rapping electrodes of an electrostatic precipitator including a rapping device, said rapping device comprising a cylinder, a free piston hammer means slidably mounted in said cylinder, an anvil forming one end of said cylinder and adapted to be connected to an electrode rapper bar, said hammer means cooperating with said cylinder and said anvil to define a low pressure chamber between the anvil and said hammer means for moving said hammer means at low velocity away from said anvil, and a high pressure chamber at the other end of said hammer means for moving said free piston at high velocity against the anvil, a source of compressed gas, first conduit means connecting said source of compressed gas to said high pressure chamber, a quick acting valve in the first conduit means for intermittently supplying slugs of compressed gas to the high pressure chamber of said rapping device, second conduit means connecting the low pressure chamber of said rapping device with said source of compressed gas, pressure reducing means in said second conduit means for supplying low pressure gas to move the hammer means at low velocity away from the anvil, the volume of said second conduit means between the low pressure chamber and said pressure reducing means being so selected as to accommodate the displaced gas in the low pressure chamber when the hammer means is actuated toward the anvil with only negligible increase in pressure, and a restricted vent port effecting communication between said high pressure chamber and the atmosphere to bleed off gas as the hammer means moves away from said anvil.

2. The invention defined in claim 1 wherein the quick acting valve in said first conduit means is time controlled.

References Cited in the file of this patent UNITED STATES PATENTS Re. 2,461 James Jan. 15, 1867 1,460,586 Howse July 3, 1923 1,480,937 Gottschalk Jan. 15, 1924 2,375,946 Reichelt May .15, 1945 2,392,088 Hamilton Jan. 1, 1946 2,473,506 Bullard June 21, 1949 2,572,385 Price Oct. 23, 1 

